UK Peptides · Research Index

Every MOTS-c (Mitochondrial Peptide) Question Answered, in 17 Studies

16-residue peptide encoded inside the mitochondrial 12S rRNA gene, identified in 2015.

Molecular weight
2174.6 g/mol
CAS number
1627580-64-6
Also written
Mitochondrial ORF of the twelve S rRNA type-c, MOTSc

Reference records: PubChem · Wikidata

17 referenced articles

Open research questions

  • What is MOTS-c?
  • What does MOTS-c stand for?
  • How does MOTS-c activate AMPK?
  • What is a mitochondrial-derived peptide?
  • How is MOTS-c different from humanin?
  • Does exercise increase MOTS-c?

Deep dive: why a peptide encoded in mitochondrial DNA is unusual

The human mitochondrial genome is 16,569 base pairs encoding 37 genes, and was considered fully characterised by the 1980s: thirteen respiratory-chain proteins, twenty-two transfer RNAs, two ribosomal RNAs. MOTS-c is encoded by a short open reading frame nested inside the 12S rRNA gene — sequence already annotated as doing something else, which is exactly why it went unnoticed. Humanin, found in 2001 inside the 16S rRNA gene, established that the genome held more than its annotation suggested; MOTS-c was found in 2015 by looking deliberately. The implication is that the mitochondrion encodes and releases signalling molecules of its own, rather than only executing instructions sent from the nucleus.

Deep dive: AMPK activation without touching AMPK

AMPK is normally activated when AMP and ADP bind its gamma subunit, making it a direct sensor of the AMP-to-ATP ratio. MOTS-c does not raise that ratio and does not bind the kinase. It inhibits the folate cycle, the one-carbon pathway feeding de novo purine biosynthesis, and the intermediate AICAR accumulates as a result. AICAR is an AMP mimetic — phosphorylated to ZMP, it binds the same regulatory site AMP occupies. So the peptide reaches a cytosolic energy sensor through one-carbon metabolism and a diffusible small molecule, which is a materially different architecture from a receptor-ligand interaction, and different again from metformin's inhibition of complex I.

Deep dive: reading a preclinical literature honestly

Roughly 250 indexed papers exist, and the overwhelming majority are cell and rodent studies. Where humans appear, the work is generally observational: measuring circulating concentrations and correlating them with age, fitness or metabolic state. The 2021 Nature Communications paper is the clearest example of the structure — the human arm measured MOTS-c before and after exercise, finding roughly a 12-fold rise in skeletal muscle against 1.6-fold in circulation, while the interventional work was done in mice. Two inferences the secondary literature routinely makes and the primary literature does not support: that a correlation between low concentrations and poor metabolic health establishes direction, and that a molecule which rises during exercise would reproduce exercise if administered.

Handling checklist

  • Store lyophilised material cold, dry and protected from light
  • Expect methionine oxidation as the primary degradation route (+16 Da per residue)
  • No reducing agent needed — the sequence contains no cysteine
  • Introduce diluent gently against the vial wall; swirl rather than shake
  • Aliquot to avoid repeated freeze-thaw cycles
  • Check mass spectrometry for +16 and +32 satellites before relying on a batch

Common mistakes

Reading exercise induction as proof that administration mimics exercise
The papers report that exercise raises MOTS-c. The reverse inference is not supported and is not claimed.
Treating human observational data as interventional evidence
Human work measures endogenous concentrations; administration studies were conducted in mice.
Assuming MOTS-c has a cell-surface receptor like humanin
No receptor is established. Its characterised activity is intracellular.
Storing reconstituted material as though it were as stable as the powder
Solution-phase material is subject to hydrolysis and oxidation; the lyophilised form is far more stable.
Overlooking WADA status in athlete-adjacent research
MOTS-c is on the prohibited list; this is relevant to any research context involving competitors.

Related reading

Reference material for laboratory research. Not medical advice, and not an offer to supply any compound for human use.